The Long Road Home

Autonomous cars could lead people to live almost 200 miles from their workplaces.

Speculation about the autonomous car—when it will become available to consumers, how it will affect the way we live, what it will mean for auto ownership—is so widespread that it's now almost a journalistic genre unto itself. There's good reason for all this conjecture: The jump from human- to software-controlled driving represents not the typical, incremental improvement to the automobile that accrues with every passing model year, but rather a massive, qualitative change in the way we get around.

As a result, when we think about the implications of the auto-auto, the big picture tends to take precedence. One prediction plausibly holds that the autonomous car will contribute to suburban sprawl, reversing the recent flow of baby boomers and millennials into cities. But there's a hulking, hairy question hidden within that idea: How much? That is, assuming that the self-driving car will cast us out into the suburbs, exactly how far-flung are we talking? Here is the secret promise—and threat—of autonomous cars. When the self-driving car achieves its full potential, it could well become perfectly normal to commute 180 miles each way. With a mature highway ecosystem consisting almost entirely of autonomous cars, you could leave your picturesque home in Bennington, Vermont, at 7:30 a.m. in order to walk through your office door in midtown Manhattan at 9.

This past year, an autonomous car, the Audi RS 7, was clocked at 149 miles per hour, and, in the auto-racing equivalent of Deep Blue's 1997 chess victory over Garry Kasparov, a different autonomous Audi defeated a human race-car driver on a closed track while traveling at speeds in excess of 120 mph. Autonomous cars that communicate with one another—perhaps while moving in concert in drag-minimizing “platoons”—could safely travel at high speeds. Autonomous platoons have already been tested at highway speeds in Spain and Sweden. As Brad Templeton, who has consulted for Google's autonomous car program, writes in his blog, it's reasonable to believe that as the technology progresses (policy and infrastructure permitting, which may take a long time), 120-mph autonomous travel could become commonplace on major highways. Dedicated lanes or even entire highways could be given over to high-speed networks of autonomous cars.

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That speed increase may sound like the sort of thing that could cut commutes in half—except that's not really how commuting works. Regardless of the mode of available transit, people tend to live a rough average of 30 minutes from where they work. This phenomenon, named Marchetti’s constant after the Italian physicist who discovered it, holds true, more or less, throughout history. (Cesare Marchetti's seminal report even theorizes about the commutes of cavemen and ancient Greeks.) Transportation breakthroughs that move people around faster, therefore, ultimately lead not to shorter commutes but rather homes that are farther from work. (Tim De Chant, editor of Nova Next, has a great explainer of this phenomenon at Per Square Mile, his excellent urbanization blog.)

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An average commute time of 30 minutes (actually closer to 25 in today's United States) may not sound like much. But when you're looking at a data set as large as that of the American commutariat, averages can be misleading. A huge number of American megacommuters make twice-daily trips of an hour or more—sometimes far more. For Marchetti's constant to hold true as commuting speeds increase, these people, who currently live in the exurbs, must move even farther out. This exodus seems especially likely given that the autonomous car commute will probably be not only be faster, but also more pleasant than current options, enabling the driver to freely read, work, and eat behind the wheel.

How far away from work will tomorrow's typical megacommuter live? Assuming that one's home and office are close to highways, and autonomous cars could maintain a speed of 120 mph, a back-of-envelope calculation reveals that someone could live in southern Vermont or Portland, Maine, and make it to our MIT office in Cambridge, Massachusetts, in less than an hour. Stretching the time window out to 90 minutes makes possible a commute from Albany to MIT.

Ninety minutes will also get you from southern Vermont or Newport, Rhode Island, to New York City.

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On the West Coast, you could drive from San Luis Obispo to Los Angeles in about 90 minutes, or from Monterey to San Francisco in an hour—time you could presumably pass by counting the money you saved by avoiding San Francisco's extortionate housing costs.

(As a side note, this high-speed vision of autonomous car travel would likely kill the local flight, such as from New York City to Boston or Washington. Why fly when you can drive to your destination in two hours door-to-door, probably for less money, while skipping security?)

A world in which a 180-mile commute is unremarkable is potentially troubling from an environmental perspective—both in terms of land use and, assuming no significant advances in energy production, carbon output. Although platooning provides a way for cars to save energy by drafting off one another, commuting at such high speeds over long distances would have an enormous carbon footprint. (That's true even for electric vehicles, assuming they're drawing power from a grid that hasn't shifted significantly toward nuclear or renewable sources, and especially if more people eschew mass transit for the comfort of personal cars.) Changes to the physical land could have implications for ecological systems, exacerbating such issues as species loss due to habitat fragmentation. And from a social perspective, the sheer distances involved would make it even easier than it already is for people to be divided in terms of both geography and the media they consume.

This future of high-speed commutes and sprawling ex-exurbs is by no means guaranteed to come to pass. Frankly, the changes in policy that would be needed to make such high speeds possible, let alone the minimal requisite changes in infrastructure, could well be enough to scuttle this whole idea, as could the rise of improved telecommuting technologies.

But still, the high-speed autonomous commute stands as a real possibility. That’s why we should start thinking now about its implications—both positive and negative. We need to make a deliberate decision about how we will live in the future, before the self-driving car makes it for us.